Microsoft released an article, 841382, on April 28th which discusses problems that have been discovered in its recently released patch, MS04-011.
According to the article problem may arise on Windows 2000 operating systems if any of three drivers (ipsecw2k.sys, imcide.sys, dlttape.sys) are loaded. People might experience lockups at boot time, the inability to log on, or 100% CPU utilization.
The article discusses a workaround for one situation that involves disabling IPSec Policy Agent. The company said it will update the article when further information becomes available.
Another article, 835732, was also released on April 28th that summaries four more articles (840997, 841384, 246507, and 224526) in addition to 841382 which also pertain to problems administrators might encounter while trying to implement the MS04-011 patch.
The problems include conditions where enhanced meta files might not be viewable, Windows NT systems might crash or not start properly, and issues with maximum partition sizes on Windows NT.